Long-term survival of a patient with acute neonatal-onset metabolic encephalopathy with carbamoyl phosphate synthetase 1 deficiency.

OBJECTIVE Long-term survival of patients with neonatal-onset carbamoyl-phosphate synthetase 1 deficiency (CPS1D), an autosomal recessive disorder characterized by repeated, life-threatening hyperammonemia, is rare. We describe the diagnosis and clinical management of a teenager with neonatal-onset CPS1D who did not undergo therapeutic liver transplantation. CASE REPORT Following emergent neonatal therapy, the patient was diagnosed with CPS1D based on clinical, radiological, biochemical and genetic analyses. Her clinical course, neurobehavioral development and therapeutic interventions are presented and discussed. RESULTS Born from nonconsanguineous parents, the proband underwent phototherapy for neonatal jaundice, associated with acute encephalopathy, apnea and cerebral edema. Based on blood and urinary biochemical abnormalities, neonatal-onset CPS1D was diagnosed. Her hyperammonemia was corrected by hemodialysis, followed by sodium benzoate, L-arginine, levocarnitine and protein-free diet therapy. Because of a relapse and persistent neurobehavioral regression by age 1, a planned liver transplantation was cancelled. At age 10, sodium phenylbutyrate was substituted as ammonia scavenger. Genetic testing revealed compound heterozygote c.2359C>T (R787X) and c.236+6T>C variants of CPS1, confirming her diagnosis. Despite severe neurological sequelae, the patient is 16 and in stable condition. CONCLUSIONS Our case suggests that early hemodialysis and pharmacologic interventions for acute neonatal hyperammonemia can improve the prognosis of patients with neonatal-onset CPS1D.